JPH02298503A - Polyethylene and copolymer composed mainly of ethylene - Google Patents

Abstract

PURPOSE: To obtain a high density polyethylene and copolymer comprising a major content of ethylene capable of giving a film having good optical properties by heating monomers under pressure with shutting off oxygen to carry out radical polymerization with part of an initiator and adding a specific initiator to the mixture cooled after the termination of reaction to continuously conduct the polymerization.

CONSTITUTION: In the first step the entire amount of monomers or a major amount of the monomers is subjected to radical polymerization under a pressure of 1,500-5,000 bar at a temperature of 40-250°C with the use of part of the necessary amount of an initiator with shutting off oxygen until the termination of polymerization. Subsequently another part of the initiator and optionally another part of the monomers are added to the reaction mixture cooled to 20-60°C and this step is continuously repeated n times (n being 3 or more) and the radical polymerization is carried out with the use of an initiator having a half- value temperature of 80-160°C in the (n-1)th step to obtain a desired polyethylene and a copolymer comprising a major content of ethylene and a minor content of a comonomer polymerizable with ethylene.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the application of monomers under pressure of 1500 to 5000 bar,
obtained by radical polymerization in at least n=3 polymerization steps with an initiator at a temperature of 40 to 250 °C and with practical exclusion of oxygen, in which the total amount of monomers or The main part is polymerized with a portion of the required initiator until the polymerization actually stops, then 20 to
Adding another part of the initiator and optionally another part of the monomer to the mixture cooled to 60°C and repeating this process in successive batches up to 0 times 1], however,(
The initiator used in step n-1) [-1 is 80 to
Half-life temperature of 160°C Conventional technology A method for producing ethylene homopolymer and ethylene copolymer at elevated pressure and in one vortex with seven revolutions at /lO°C is as follows:
There are already some 1. r stated in the license specification. The reaction takes place in a tubular reactor (German Patent Application No. 2557653; Specification, Federal Republic of Germany TJ).
Patent Application Publication No. 2558266 Specification, German Patent Application No. 3308926 Specification, French Patent (■3) No. 2335531 Specification, Inuita Patent (B) No. 10108/17-Re Specification) Implementation or a combination of a reactor with an inverted mixing device and a downstream tubular reactor (German Patent Application No. 2 322 553, Helgie Patent No. 710)
No. 392 specification) is carried out. The density of the ethylene-Φ combination produced in this case is 925 ky/m'' or less.

If you want to use a large number of areas, please add @/r to 925.
It is necessary to use a polyethylene having a density around n3 to I:. This is because only this polyethylene has the corresponding optical properties. When this polyethylene was processed under increased pressure and temperature,
It is possible to produce the compound in the F case, but it encounters significant difficulties. This is because Rancal polymerization technology allows for higher crystallinities and densities only at relatively low polymerization degrees.
cr '“Polymcrc Werkstoffa”
, Volume 11-T c h n 0 + (1g i
[! 2. Gcorg l'hicme Verl
ag SLuLtgart ] 98 /I.

(page 31), since the conversion rate is thereby clearly reduced. This results in that in the production of polyethylene of this type, conversions of less than 25% are often achieved (US Pat. No. 3,660).
10 books in No. 370).

Patent Application No. 2,748,263 of the Federal Republic of Germany discloses that the polyethylene is 25% within the desired density range.
A method for manufacturing the same at a conversion rate similar to that of the previous example is described. In this case, a reactor 91+, which is extremely expensive in terms of equipment, is required, in which case the cross section of the reactor is clearly grounded several times and the reactants are transferred at least 0.307 m2/s.
It is necessary to convey through the reaction tubes at a flow rate of 111 and to configure the reactor in such a way that all reaction zones are connected to a cooling zone and a work-up zone. Using this method of equipment and process technology, polyethylene can only be produced at very high costs by the method described in No. 111j within the preferred range.

OBJECTS OF THE INVENTION Accordingly, it is an object of the present invention to eliminate the disadvantages mentioned in item 1jII and to achieve an acceptable cost in terms of equipment and processing technology.
The aim is to produce ethylene-in-ethylene polymers and ethylene copolymers having densities of around 1 kg/m3 and good optical properties.

Means to solve problems Accordingly, 19 combinations were found that were marked 1￥r.

The method used for the production of the polymer according to the invention consists of l(1
Germany 1. It can also be used for t"1 go, or it can be used for another single 41
Radical copolymerization of one monomer with ethylene under crystal pressure can also be used for copolymerization of ethylene with another H monomer under ni+ conditions. For this purpose, particular mention may be made of α β-ethylenically unsaturated C3-08 carbonic acids, in particular maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid and crotonic acid. -β-ethylenically unsaturated C4-015-carboxylic acid ester or monoanhydride, in this case methyl methacrylate-1, ethyl acrylate, n-butyl acrylate-1, methacrylic acid hydrate, hydrate maleic acid and itaconic anhydride are preferably used.The comonomer content of the copolymers according to the invention is preferably 2/10%, in particular 2
Do not go around 0% once.

The polymerization reaction is carried out at a pressure of 500-5000 bar and an i (i! degree of /10-250'C). In this case, a pressure of 1500-3500 bar and a temperature of 10
Temperatures between 0 and 250'C are suitable.

Polymerization according to the method of the present invention is carried out at 80 to 60'C.
' - The degree of depletion is initiated by the addition of a radically decomposing initiator. The half-life temperature is the temperature ffj at which half of one starting agent dissolved in benzole decomposes in one minute.

Examples of such initiators include: di-2-ethylhexyl-peroxydicarpone-1-, dicyclohexyl-peroxydicarpone-1-, dicetyl-peroxydicarpone-1- 1. Cumyl perneodecanoate, tert-amyl perbivalate, t-butyl perneodecanoate, t-butyl permaleinate and preferably tert-butyl perbivalate and tert-butyl ruber isononanoate. . Optionally, a single 1'' polymerization step can also be effected with an initiator having a half-life up to 250 DEG C., such as tert-butyl perbenzoate or methyl isobutyl ketone peroxide. The initiators, alone or in mixtures, can be used in amounts ranging from 0.5 to IOOppm/based on the amount of monomer.
h, preferably a concentration of 0,'5 to 50 ppm:
Can be used at degrees. In this case it has proven advantageous to use the initiator in dissolved form. Suitable solvents are, for example, aliphatic hydrocarbons, especially octane or isododecane.

The molecular size of the claimed polymer can be controlled by adding regulators in a conventional manner. Particularly suitable regulators are aliphatic hydrocarbons, ketones and aldehydes, in which case propionic aldehyde is preferably used.

According to the invention, the production of the polymer is carried out with actual exclusion of oxygen.

In this case, the process is carried out in at least three successive steps, the polymerization having to be started anew in every step by addition of the corresponding initiator. For this purpose, a tubular reactor is suitable, in particular with a series of inlet positions for the initiator and optionally another "11 series of supply reservoirs" positions. In this case, The tubular reactor has a length/diameter ratio of at least 1000, in particular 2000'' for lengths of 50 to 1000 m and is arranged in a wound configuration. The heat of reaction generated is removed by cooling the reactor walls from the outside with water. If necessary, this tubular reactor is adjoined to a reactor with an inverted mixing device, in particular a stirred autoclave. Historically, in this case, one
It is possible to cool down the mixture in a tubular reactor using a heat exchanger in front of the person. However, generally this method is carried out without a heat exchanger. Furthermore, the reactor used in this method has a series of temperature measuring devices inside the reactor, so that the temperature course during the polymerization can be observed.

In one preferred embodiment, the reaction mixture of ethylene and modifier is first compressed to a pressure of 1500 bar, heated to above 100° C. and subsequently subjected to a tubular reaction together with a portion of the initiator. In this tubular reactor, polymerization starts immediately after decomposition of the initiator. In this case, the cooling of the reactor must be adjusted to such an extent that the temperature inside the tube does not exceed 250°C. Already after a short time, a temperature profile occurs along the tubular reactor that depends on the conversion of the polymerization. In this case, the gradual decrease in the reaction is
This is indicated by a decrease in temperature inside the tube. 2 than max
If a temperature 0-60° C. lower is achieved, the polymerization is started again by adding another amount of initiator. Due to this, the temperature difference again becomes clearly 1 - I, in which case care must be taken by suitable cooling means to ensure that the maximum temperature achieved in this case is below 250°C. result.

This process can be repeated at any time along the reaction tube by freshly feeding other initiators. Thereby a series of different polymerization stages is formed in the reactor, all of which are characterized by a constant temperature maximum. According to the invention, the method has at least three steps. Optionally, still cold ethylene or optionally preheated ethylene can be added to the reaction mixture together with the initiator, either at the same location or at a spatial distance therefrom. K-C-kiru. The average residence time of this mixture in the tubular reactor is from 30 to 300 seconds, preferably from 30 to 120 seconds.
There is C. After the reaction mixture has been discharged, the combined product is separated from unused ethylene by depressurization, and this unused ethylene is preferably recycled into the reactor.

The described process can likewise be carried out in a reactor with an inverted mixing bag Iv() and in a downstream tubular reactor. The temperature increase is limited to 230° C. After the gradual reduction of the polymerization, the reaction mixture, still together with the unused single It-form, is passed through high-pressure pipes, optionally still connected to a heat exchanger. introduced into a tubular reactor, where the method
It is further carried out in the same manner as described above. The average residence time of the mixture is 10-1 in a reactor with an inverted mixer.
00 seconds, preferably 10 to 30 seconds, and in the case of tubular reactors, iQ to 200 seconds, preferably 10 to 100 seconds''C.

The polymer according to the invention has, as desired, 925 k
, has a density of 4 - around y/m3, in many cases rather than 930, a density of -1 - around y/m3. The melt flow intex of the polymer according to the present invention is
0.0 as measured by D I N 53735, respectively.
]~] 00! / / ] Within the range of 00m1, 4-1
+' is within the range of 0.2 to IO4l/] 00ml. Melt Flow Intex is DIN5373
This corresponds to 4It of polymer pressed in 10 minutes at a temperature of 190"C and a jn jtt of 2.]6kh by a test apparatus standardized to 5. Films made from this polymer have a good This is particularly true for the relatively low scattered light fraction (according to DIN 53d90) and the increased gloss (according to DIN 67530). -C. According to the method of the present invention, 925 @/m
It is possible to produce polymers with densities of 1 -9.degree. with a conversion of 25%. Another advantage is that high-pressure technology can be used in conventional reactors, i.e. without resorting to reactors with variable cross sections, for example, and that the process can be carried out without special industrial outlays. It is in. German Patent Application No. 27/1 8263: - Contrary to what is stated in the specification, the desired coalescence is also obtained when the reaction mixture is passed through the reactor with a flow rate lower than 0.3 m2/s.

The monomers according to the invention are suitable as coating materials and photolacquers due to their good optical properties, in particular for producing films.

Examples Examples 1 to 3 and the corresponding comparative examples Δ and B are 4
It was carried out in a tubular reactor with a length of 20 meters and a length/diameter ratio of 25,000. The polymers obtained in Examples 1 to 3 had good optical tl'Y'j, in particular low scattered light fraction and high gloss (Table 1). The density of this polymer is 930 k y / +n 3
It was going around 1-.

11 of the initiator added in the test was IIpm
/h and is always relative to the ethylene used.

Example 1 2.3 t/h of ethylene together with 2 C/h of propionic aldehyde as regulator at 280 t/h in a high-pressure recompressor.
It was compressed to 0 bar, heated to 145°C and fed into a tubular reactor. Polymerization of tert-butyl-berbivalate and tert-butyl-perisononanoe h 3,8 pp.
triggered by the addition of m/h. After the reaction gradually decreases, jp
．． and 5-butylrubelpivalate, respectively.

It was started again by two additions of 4 ppm/h and a subsequent addition of 2, 2 ppm/h of tert-butyl-perisononanoate, thus a total of 4
The same #l+'1 degree maximum was formed, but all of these did not exceed 240°C. average fl of the reaction mixture
j7 residence time is 80 seconds, flow rate is 0,]]m2/
It was S. Ethylene conversion was 255%.

Example 2 2.3 t/h of ethylene were fed into a tubular reactor under the same conditions as described in Example 1 and polymerized. After gradual reduction of the reaction, the polymerization was started with 14.2 pp of tert-butyl-perpivalate.
m/h and subsequently tert-butyl-periiso7
Each time was restarted by addition of 7.6 ppm/h of nanoate, whereby a total of four temperature maxima were formed, all of which were less than 250° C. The average residence time was 80 seconds and the average flow rate was 0.
．． 1] m2/S. In this reaction, 26.5% of the ethylene originally used was converted.

Example 3 Ethylene 1. I5 t/h together with propionic aldehyde 2 Q/h as regulator in a high-pressure recompressor at 28
00 bar, heated to 145°C and fed into a tubular reactor. Polymerization ゛ Reactor person［］
1.3 ppm/h of tert-butyl-ruviva-ate and 2.5 ppm of tert-butyl-periiso7 nanoate at the position
Inspired by m/h. After decreasing the reaction, the polymerization was carried out at 2,3 ppm/tert-butyl-periso7 nanoate.
h and tert-butyl-perpivalate 1.6 ppm/h
was restarted at another position by addition of . The mixture heated by the heat of polymerization was heated to 1.15 t/h of ethylene previously compressed to 2800 bar and heated to 70°C.
Cooled by feeding. Subsequently, in the two other reactor positions, tert-butyl perpivalate 3.8
ppm/h and tert-butyl-beriso7 nanoate 3
, 0 ppm/h and thus a total of four temperature maxima were formed, in this case 235 °C
'', it didn't turn. The average residence time of the mixture was 70 seconds, the flow rate was 0.22 m27 s, and the ethylene conversion was 26.0%.

Comparative Example A Polymerization is carried out under the same conditions as in Example 2, but the polymerization is
Sec-Butyruperisononanoate 7 times, 0 p
It was started again by adding pm/h. in this case,
The ethylene conversion was only 21.9%.

Comparative Example 13 Polymerization was carried out as described in Example 1, the only difference being that instead of tert-butyl perisononanoate, 1
Methyl isobutyl ketone hydroperoxide having a half-life temperature of 90°C was used. The product obtained in this case had a density of less than 925 kg/m3.

Comparative Examples A and B The polymers obtained in these tests had significantly poorer optical properties compared to Examples 1-3 (Table 1).

The splicing ability of these polymers was insufficient.

-l+! - Examples/1 to 6 were prepared in exactly the same manner as Comparative Examples C-E.
A stirred autoclave with a capacity of 5μ, a J-type autoclave connected to it, a length of 200 meters and
It was carried out in a polymerization system consisting of a tubular reactor with a length/diameter ratio of 3300. jT′ obtained in Examples 4 to 6
1 coalescence had good optical properties, especially low scattered light percentage and high gloss (Table 2). The density of this polymer is 930 ky/m''.

Of the initiator added in the test! -11 is stated in ppm/h and is always relative to the ethylene used.

Example 4 Ethylene 1. /lt/h with 1.40/h of propionic acid altehyde as a regulator and compressed to 2800 bar in a high-pressure 11■ compressor and the gas population i! at 30°C. 1.
1. Once fed into a stirred 1-crepe. Polymerize tert-butyl-pervivalate 10.

Starting with 'I ppm/h, the contents of the autoclave were thoroughly mixed using a stirrer at a speed of 1300 rpm. In this case, the average residence time was 25 seconds. The maximum temperature in the autoclave was 211°C.

Subsequently, the reaction mixture was fed into the tubular reactor via an insulated high-pressure tube and the 1F reaction was restarted with tert-butyl perisononanoate l, 5 ppm/h. This process was repeated in another position in the tubular reactor with the same initiator 0, 95 ppm/h, thus a total of two temperature maxima were formed there, both of which were below 230 °C. It was below. The average residence time was 710 seconds and the ethylene conversion was 25.
It was 5%.

Example 5 In the same manner as in Example 4, the differential force or ethylene 1/It/h
Tertiary butyl Belpi Valley 1 in a stirred autoclave
.] 4.4 ppm/h, the maximum temperature in this case was 2200C.

The reaction mixture is then introduced into a tubular reactor via an insulated high-pressure tube and the tert-butyl periso7 nanoate]. 65 ppm/h was added.

After tapering off of the polymerization, the 11th batch was restarted with a second batch of 1.15 ppm/h of Buzalbel Isononanoel. Thereby a total of two 7!1,
A maximum of 1 degree occurs, in which case the maximum of the first 4 degrees is 24
2°C, and the first temperature maximum was 235°C. The average residence time of the mixture is 20 seconds for the stirred autoclave and 40 seconds for the tubular reactor.
It was seconds. 269% of the ethylene originally used was converted.

Example 6 0.7 t/h of ethylene is compressed with modifier and 1.12 t/h of propionic acid altehyde using a high-pressure compressor to 2800 bar and heated to 30° C. and fed into a stirred JXIJ autoclave. The reaction was initiated with 1.10 ppm/h of tert-butylperpivalate and the contents of the reactor were stirred at 130 or
speed of pm j. The average residence time in the reactor was 50 seconds. The temperature in the reactor was
2] It was 0'C.

Before entering the contents of the autoclave into the tubular reactor,
It was mixed with 0.7 t/h of ethylene previously compressed to 2800 bar and heated to 60'C and fed into a tubular reactor. In the position of this tubular reactor, the polymerization was carried out at a rate of tert-butyl-perpyhalet l-0, 9 ppm/h and tert-butyl-perpihalet h-l, 8
It was started at 111 ppm/h. reaction iv
After iKL, each of the tert-butyl-perisonoj-y 1-0.95
ppm/h or 11 ppm/h, so a total of three temperature peaks were formed, all below 235°C. The average residence time was 45 seconds and the ethylene conversion was 2762%. Tertiary butyl only once in the container
It was restarted by adding 1.5 ppm/h of berisononanoate. The ethylene conversion obtained in this case was only 22.5% of the solder.

The comparative example was worked under the same conditions as in Example 6, the only difference being that the ethylene added to the mixture discharged from the stirred autoclave contained 4 ppm of air, in connection with which the subsequent No initiation of polymerization occurred. The polymer obtained in this case was still 922.5ky/
It had a density of only m3. The conversion rate of ethylene is 2
It was 55%.

Comparative example E Polymerization was carried out under the same conditions as described in Example 5.

The only difference in the tests performed was the use of methyl isobutyl ketone hydroperoxide instead of tert-butyl perisononanoate. In the two polymerization zones, the maximum temperature is 2
The temperature was below 70°C. The polymer obtained in this case is
92] and had a density of less than 5 kg/m3. The ethylene conversion rate was 27.8%.

Comparative Examples C-E The polymers obtained in these tests had significantly poorer properties (see Table 2) compared to the polymers according to Examples 4-6.

123=

Claims (1)

[Claims] Monomers at a pressure of 1500-5000 bar, 40-25
obtained by free-radical polymerization in at least n=3 polymerization steps with an initiator at a temperature of 0° C. and with practical exclusion of oxygen, in which case the entire amount or major part of the monomers is present in the first step. One part of the initiator required is used to polymerize until the polymerization actually stops, after which the other part of the initiator and optionally other monomers are added to the mixture cooled to 20-60°C. and repeat this process in successive steps up to the nth step, provided that the initiator used in the (n-1)th step is polyethylene and ethylene with a half temperature of 80-160°C. Copolymers with a major content and a minor content of comonomers polymerizable with ethylene.